1. Field of the Invention
The present invention relates to a heating element control circuit and a heated handgrip of the type utilized on motorcycles, ski mobiles, and other vehicles employing handlebars with handgrips on them.
2. Description of the Prior Art
Heated handgrips have been utilized for many years on motorcycles, ski mobiles, and other vehicles, particularly those in which a user's hands are exposed to the ambient atmosphere when operating the vehicle. A conventional heated handgrip is normally powered by an electrical current passing through one or more electrical resistance heating elements. The passage of electrical current through high resistance electrical wires generates considerable heat. The electrical heating elements of a handgrip employed, for example, on a motorcycle, are normally embedded within a nonconductive material of which the grip is formed, for example rubber or plastic. Many conventional electrical, heated grips are constructed of rubber over nylon.
One recurrent problem that has existed with conventional grips is that they are damaged by improper or inattentive use. For example, a motorcycle rider is typically provided with some type of manual control to turn the heating elements of the motorcycle handgrips off and on, and even to adjust the temperature. If the rider is traveling at a high speed through frigid air, the controls for the grips will normally be adjusted to provide a great deal of heat. On the other hand, if the rider is traveling at slower speeds in heavier traffic and the ambient air temperature is not all that cold, only a small amount of electrical current to the resistance heating elements of the grips is appropriate.
Heated grips are often damaged due to overheating when the heating elements are left at a high heating level when they should be turned off. For example, a motorcycle rider may adjust the temperature of the grips to provide a considerable amount of heat when riding at high speed through cold air but may forget to turn electrical current to the heating elements down or off when the rider arrives at a destination and parks the motorcycle. The nylon materials of which handgrips are often formed typically melt at a temperature of between about three hundred fifty degrees and about four hundred fifty degrees Fahrenheit, depending upon the particular type of nylon. If the heating elements of heated automotive vehicle handgrips are left on high for a prolonged period of time in relatively warm ambient air, the material of which the grips is constructed will become distorted, melt, or otherwise become degraded. This can lead to a very dangerous situation in which the throttle control in the grip will lock up due to distortion. Also, since the cost of heated cycle handgrips is not inconsequential, forgetfulness in maintaining a proper temperature of the heating elements can be quite costly.
Temperature control systems do exist for heated vehicle handgrips. However, conventional heated handgrips for motorcycles and snowmobiles do not maintain a particular temperature. Rather the user selects a desired electrical current level for heating the grip and electrical current is fed to the electrical resistance heating element constantly at a current magnitude proportional to the setting. However, conventional systems do not include control circuitry for maintaining a constant temperature, but rather only a specified level of electrical current. Consequently, the actual temperature of the article will vary significantly, unless manually adjusted by the user, since the same electrical current is supplied to the electrical resistance heating element irrespective of whether the vehicle is moving at a high rate of speed in cold weather, or whether the vehicle is stopped. In conventional systems for heated motorcycle and snowmobile handgrips the user must manually alter temperature settings in order to increase or decrease electrical current to the handgrip. Moreover, conventional systems involve a continuous supply of electrical current to the heating element. If the ambient temperature about the vehicle handgrip increases, overheating of the grip can easily occur unless the user is extremely diligent in monitoring the temperature setting.
An electrical heating control circuit according to the invention can be located anywhere on the vehicle. However, the system of the invention is preferably provided with a hollow, handgrip core located within the hollow vehicle handlebar and the electrical heating control circuit is located within that core. This represents a further improvement over conventional electrical resistance heat control systems which are often rather bulky and involve extended runs of wire to the grips from control circuits located on the frames of motorcycles or other vehicles. The lengthy run of wires in conventional heating current selector systems reduces the ability of a conventional heating adjustment circuit to provide an appropriate amount of heat in changing ambient conditions. Therefore, conventional vehicle handgrip temperature setting controls have proven unsatisfactory.